1. Field of the Invention
The invention relates to an ink jet printer, and relates particularly to an ink jet printer that executes a nozzle purging or refresh operation to prevent nozzle clogging.
2. Description of the Related Art
Various control means and methods have been proposed to prevent ink clogging inside the nozzles of ink jet printers that print by ejecting ink from such nozzles. These various control means and methods include defining a particular number of nozzle purging operations to clear the nozzles based on the elapsed time of continuous no-printing of the ink jet head. One such method is described in Japanese patent laid-open number 1-281950 (1989-281950), and also in U.S. Pat. No. 5,572,242, which is commonly assigned and has a common inventor with the present application.
The conventional ink jet printers described above use methods whereby the number of nozzle purging occurrences increases in proportion to the down time (no-ejection time) of the ink jet head. This method does not, however, consider ink characteristics, and therefore does not ensure the optimal ink purging volume for a particular ink type. This results in wasteful ink consumption and printing without sufficient ink purging or complete nozzle refreshing, which can cause printing defects.